know the identity the third victim killed in the blast, 23-year-old lingzi lu. 29-year-old krystle campbell and richard martin were killed. >> reporter: good morning, richard. let's talk about the investigation first. the authorities have been vesting photographs, images from anybody in the public. it appears that is now paying off, perhaps the most successful images coming from a security camera at lord & taylor across the street from the finish line. but those images show what appears to be somebody taking duffel bags and placing them at the spot where the bomb exploded. so there's a major focus of attention on those pictures trying to analyze them to see if they can then lead to who may indeed be a suspect. meantime, as you mentioned the president will be making a visit here to boston for an interfaith memorial service. the president will be joined here by so many bostonians. of course, one of the concerns, security has, because it's another large gathering if somebody would have tried to do something. they've told folks if they're gathering, they may not bring bags, backpacks.